The statistical risk for a person to be killed by space debris is extremely small.

Although large pieces of scrap, such as burned-out rocket stages, sometimes fall back to Earth, the planet's surface is made up of around 70 percent water - so crashed aircraft usually end up in the world's oceans.

"In the 67 years of space travel, thousands of tons of artificial space objects have re-entered the atmosphere," says Tim Flohrer, space debris expert at the European Space Agency (Esa).

"The pieces that made it to the surface have only very rarely caused damage, and there has never been a confirmed report of human damage."

And yet ESA was happy that the old environmental satellite ERS-2, which weighs around two tons, entered the Earth's atmosphere on Wednesday over the deserted North Pacific - and not near a metropolis.

Images from the German space observation radar Tira now show the satellite's final hours.

Tira is operated by the Fraunhofer Institute for High Frequency Physics and Radar Technology in Wachtberg near Bonn.

The 240-ton antenna is 34 meters tall and is protected from environmental influences by a 47.5-meter radome, i.e. an antenna dome.

Last Monday to Wednesday, the facility observed ERS-2 during its final orbits around the Earth.

The images show that it had already dismantled the satellite before its final crash.

What is particularly noteworthy is that the solar panel, measuring more than eleven by two meters, initially bent and then even detached from the rest of the construction.

This is interesting for predicting future satellite crashes.

The computer models used for this have so far assumed that a satellite is a stable object right up to the end.

But if parts fall off beforehand, it may behave differently than predicted.

Targetedly sent to lower orbit

After its launch in April 1995, ERS-2 measured, among other things, how ice streams in the polar regions are disappearing and the seas are heating up.

According to ESA, thousands of scientific publications have been published based on its data.

However, it had to be shut down in September 2011.

There had previously been technical problems, for example with the memory, but also with the satellite's attitude control.

However, there was still enough fuel in the tanks to send the device to a lower orbit.

This was intended to prevent collisions with other satellites.

Over the years, the satellite sank to an ever lower orbit.

His end was therefore foreseeable.

From an altitude of 80 kilometers, the friction in the outer layers of the atmosphere is so great that the only option is to fall.

At Esa, the disposal of ERS-2 is seen as a success story.

At some point in the future, the organization will also have to deal with the crash of the much larger Envisat satellite, with which contact has been lost since 2012.

It is currently traveling at a height of around 760 kilometers.

In principle, a huge target races around the earth 14 times a day - for the next 150 years or so.

If there were a collision with another satellite or a piece of junk, a huge cloud of debris could be created.

And: The chance of being hit by space debris on the ground may be small, but it is not zero, according to calculations by a team led by Michael Byers from the University of British Columbia in Vancouver.

Accordingly, there is a mathematical risk of at least ten percent that one or more people will be killed by space debris within ten years.

Planning such crashes as precisely as possible can save lives, at least in rare cases.